I don’t think you can recoup money transferred from the sinking fund in accordance with s71(2) via a levy to the Admin Fund. This would not be addressing the sinking fund deficit.
IMO s76 allows the OC to determine levies to both admin and/or sinking fund so long as a budget estimate is agreed to at the same meeting. There is nothing to say that this can not be a resolution to amend the budget (previously passed at the AGM) mid year and subsequently levy an additional sinking fund contribution (or increase the current contributions) to pay back the money transferred.
This gets us around the messy business of transferring a “surplus” from the admin fund to the sinking fund. BTW – s72 deals with how to distribute surplus funds. They should be paid back to the owners in proportion according to unit entitlement and via passing a unanimous resolution.
I believe it follows that transferring a “surplus” from the admin fund to the sinking fund should be by way of budgeting a future deficit in the admin fund and increase the sinking fund by that same amount.